source: rtems/cpukit/libnetworking/net/ethernet.h @ 39e6e65a

/*
 * Fundamental constants relating to ethernet.
 *
 * $Id$
 *
 */

#ifndef _NET_ETHERNET_H_
#define _NET_ETHERNET_H_

/*
 * The number of bytes in an ethernet (MAC) address.
 */
#define ETHER_ADDR_LEN          6

/*
 * The number of bytes in the type field.
 */
#define ETHER_TYPE_LEN          2

/*
 * The number of bytes in the trailing CRC field.
 */
#define ETHER_CRC_LEN           4

/*
 * The length of the combined header.
 */
#define ETHER_HDR_LEN           (ETHER_ADDR_LEN*2+ETHER_TYPE_LEN)

/*
 * The minimum packet length.
 */
#define ETHER_MIN_LEN           64

/*
 * The maximum packet length.
 */
#define ETHER_MAX_LEN           1518

/*
 * A macro to validate a length with
 */
#define ETHER_IS_VALID_LEN(foo) \
        ((foo) >= ETHER_MIN_LEN && (foo) <= ETHER_MAX_LEN)

/*
 * Structure of a 10Mb/s Ethernet header.
 */
struct  ether_header {
        u_char  ether_dhost[ETHER_ADDR_LEN];
        u_char  ether_shost[ETHER_ADDR_LEN];
        u_short ether_type;
};

/*
 * Structure of a 48-bit Ethernet address.
 */
struct  ether_addr {
        u_char octet[ETHER_ADDR_LEN];
};

#endif